The present invention relates to a yarn winding apparatus, and more specifically, it relates to a yarn winding apparatus wherein a yarn is wound on a bobbin tube at a constant wind ratio.
Winding a yarn at a constant wind ratio has a remarkable feature in that such winding can easily prevent ribbon-winding from occuring. Therefore, a yarn package wound at a constant wind ratio can be very smoothly unwound at high speed. Such a yarn package is particularly required with the development of water or air jet looms in which looms a weft yarn is unwound from a supply yarn package at high speed, such as at about 1,200 m/min.
In a conventional yarn winding apparatus which winds a yarn at a constant wind ratio, a winding spindle for mounting a bobbin is driven by a motor. The driving power for a traverse means is transmitted from the winding spindle by means of a timing-belt or gears, whereby the wind ratio is kept constant. However such a conventional yarn winding apparatus with a constant wind ratio has several problems as described below.
According to the conventional winding apparatus, it is difficult to wind a yarn at high speed, e.g. at several thousand meters per minute, because of the mechanical transmission of the driving power from the winding spindle to the traverse means. If the winding is carried out at high speed, problems in lubrication of the gear device arise and slippage between the belt and the pulley which is caused by the difference in rotational speeds of the winding spindle and the traverse means occurs. In addition, the noise level is greatly increased at high speeds.
Another problem of the conventional winding apparatus is the difficulty in changing the wind ratio. The wind ratio should be changed in accordance with various conditions such as the type of yarn material, the denier of the yarn, the quality of the yarn, the size of the yarn package to be formed and the like. However, according to the mechanical transmission in a conventinal apparatus, changing the wind ratio is very troublesome.
Further problems with the conventional winding apparatus are encountered in the space necessary for the winding apparatus and the cost of the installation. In a conventional winding apparatus having a plurality of winding units, each winding unit comprises, as a unit, a yarn tension sensor, a speed changing means for controlling a motor of a winding spindle based on a signal issued from the yarn tension sensor, and a gear device for transmitting the driving power from the winding spindle to a traverse means. As a result, a conventional winding apparatus requires considerable space and high installation cost.